Kong L, Zou Y, Li XX, Zhang XP, Li X. Rhodium-catalyzed enantioselective C-H alkynylation of sulfoxides in diverse patterns: desymmetrization, kinetic resolution, and parallel kinetic resolution.
Chem Sci 2023;
14:317-322. [PMID:
36687346 PMCID:
PMC9811495 DOI:
10.1039/d2sc05310a]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 12/01/2022] [Indexed: 12/05/2022] Open
Abstract
Rhodium-catalyzed enantioselective C-H alkynylation of achiral and racemic sulfoxides is disclosed with alkynyl bromide as the alkynylating reagent. A wide range of chiral sulfoxides have been constructed in good yield and excellent enantioselectivity (up to 99% ee, s-factor up to > 500) via desymmetrization, kinetic resolution, and parallel kinetic resolution under mild reaction conditions. The high enantioselectivity was rendered by the chiral cyclopentadienyl rhodium(iii) catalyst paired with a chiral carboxamide additive. The interactions between the chiral catalyst, the sulfoxide, and the chiral carboxylic amide during the C-H bond cleavage offer the asymmetric induction, which is validated by DFT calculations. The chiral carboxamide functions as a base to promote C-H activation and offers an additional chiral environment during the C-H cleavage.
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